Britney Spears' dad begged Justin Timberlake to perform with her

Britney Spears' dad begged Justin Timberlake to perform a series of concerts with the fallen pop princess, it has been claimed.

Jamie Spears reportedly contacted Justin -- Britney's ex-boyfriend -- in a desperate bid to "jump start" the troubled star's career -- but Justin refused to perform with her.

A source said: "Jamie wanted Justin to help Britney. Justin had seriously considered doing a couple of concerts with Britney later this year to jump start her career.

"Jamie knows Justin has so much goodwill in the music industry and his support would do her good.

"But Justin told Jamie that while he still cares deeply for Britney and wishes her all the best, it isn't going to happen."

Although Justin, 27, told Jamie that he was "too exhausted" to tour with the Toxic singer, the real reason behind his refusal was said to be his current girlfriend Jessica Biel.

The source added to the National Enquirer: "Justin said he was exhausted from his 18-month world tour, which ended in December.

"He said he had no plans to take to the stage in 2008. But he left out the most important reason - he is getting ready to propose to Jessica, who has a jealous streak.

"The last thing Justin wants right now is to rock their relationship by getting cosy with an old flame."

Last month, it was claimed that mother of two Britney, 26, was busy rehearsing for a world tour to promote her new album 'Blackout'.

A source said: "Britney will be leaving the country in the next few weeks, after training in privacy for a month."